Dark pigments reflecting ir radiation, method for the production thereof, and use thereof

Abstract

The invention relates to an IR radiation-reflecting pigment comprising a platelet-shaped, metallic, IR-reflecting core, the IR radiation-reflecting core being provided with a substantially enveloping coating whose absorption for IR radiation is substantially low, and the IR-reflecting pigment being substantially dark. The invention further relates to a method of producing these pigments and also to the use thereof.

1 . An IR radiation-reflecting pigment comprising a platelet-shaped, metallic, IR radiation-reflecting core,
 wherein   the IR radiation-reflecting core is provided with a substantially enveloping coating whose absorption of IR radiation is substantially low, and wherein the IR radiation-reflecting pigment is substantially dark.   
     
     
         2 . The IR radiation-reflecting pigment of  claim 1 ,
 wherein   the coating which substantially envelops the core and whose absorption of IR radiation is substantially low comprises dark color pigments and a matrix.   
     
     
         3 . The IR radiation-reflecting pigment of  claim 2 ,
 wherein   the dark color pigments are disposed in at least one location selected from in, on and under the matrix of the coating whose absorption of IR radiation is substantially low.   
     
     
         4 . The IR radiation-reflecting pigment of  claim 2 ,
 wherein   the dark color pigments have an average primary particle size of 10 to 1000 nm.   
     
     
         5 . The IR radiation-reflecting pigment of  claim 2 ,
 wherein   the dark color pigments are selected from the group consisting of spinel mixed phases, iron oxides, iron-manganese mixed oxides, perylenes, and mixtures thereof.   
     
     
         6 . The IR radiation-reflecting pigment of  claim 2 ,
 wherein   the dark color pigments are present in an amount of 20% to 80% by weight, based on the weight of the total IR radiation-reflecting pigment.   
     
     
         7 . The IR radiation-reflecting pigment of  claim 2 ,
 wherein   the dark color pigments are disposed substantially uniformly around the IR radiation-reflecting core.   
     
     
         8 . The IR radiation-reflecting pigment of  claim 1 ,
 wherein   the coating whose absorption of IR radiation is substantially low comprises metal oxide.   
     
     
         9 . The IR radiation-reflecting pigment of  claim 8 ,
 wherein   the metal oxide is selected from the group consisting of silicon dioxide, aluminum oxide, aluminum hydroxide, boron oxide, boron hydroxide, zirconium oxide, and mixtures thereof.   
     
     
         10 . The IR radiation-reflecting pigment of any of  claim 1 ,
 wherein   the coating whose absorption of IR radiation is substantially low comprises at least one selected from at least one of organic polymers and binders.   
     
     
         11 . The IR radiation-reflecting pigment of  claim 10 ,
 wherein   the at least one of organic polymers and binders has a glass transition temperature of above 75° C.   
     
     
         12 . The IR radiation-reflecting pigment of  claim 1 ,
 wherein   the matrix is present in a fraction of 2% to 30% by weight, based on the weight of the total IR radiation-reflecting pigment.   
     
     
         13 . The IR radiation-reflecting pigment of  claim 1 ,
 wherein   the IR radiation-reflecting core is a platelet-shaped metal pigment.   
     
     
         14 . The IR radiation-reflecting pigment of  claim 1 ,
 wherein   the IR radiation-reflecting core is a platelet-shaped metal pigment having a size in a range from 3 to 250 μm.   
     
     
         15 . The IR radiation-reflecting pigment of  claim 1 ,
 wherein   the IR-reflecting core is a platelet-shaped metal pigment having a d 50  value of the cumulative undersize distribution in a range from 25 to 150 μm.   
     
     
         16 . The IR radiation-reflecting pigment of  claim 1 ,
 wherein   the IR-reflecting core is a platelet-shaped metal pigment having an average thickness in a range from 0.25 to 4 μm.   
     
     
         17 . The IR radiation-reflecting pigment of  claim 1 ,
 wherein   the IR-reflecting core is a platelet-shaped aluminum pigment.   
     
     
         18 . The IR radiation-reflecting pigment of  claim 1 ,
 wherein   the IR-reflecting core is a platelet-shaped aluminum pigment, the coating whose absorption of IR radiation is substantially low comprises SiO 2 , and the dark color pigment embedded into the coating is selected from the group of complex inorganic chromatic pigments.   
     
     
         19 . A method of producing an IR radiation-reflecting pigment of  claim 1 ,
 wherein   a platelet-shaped, metallic, IR radiation-reflecting core is enveloped with a dark coating whose absorption for IR radiation is substantially low.   
     
     
         20 . The method of producing an IR radiation-reflecting pigment of  claim 19 ,
 wherein   the coating comprises dark color pigments and a matrix.   
     
     
         21 . The method of producing an IR radiation-reflecting pigment of  claim 20 ,
 wherein   the dark color pigments are applied together with metal oxide, using a wet-chemical sol-gel process, in a substantially enveloping fashion around the IR radiation-reflecting core.   
     
     
         22 . The method of producing an IR radiation-reflecting pigment of  claim 21 ,
 wherein   SiO 2  as metal oxide is applied by a wet-chemical sol-gel process to the IR radiation-reflecting core.   
     
     
         23 . The method of producing an IR radiation-reflecting pigment of  claim 19 ,
 wherein   a dispersion comprising a volatile organic solvent, IR radiation-reflecting cores, dark color pigments, and at least one material selected from at least one of organic polymers and binders is spray-dried with spraying.   
     
     
         24 . A method for producing a material selected from the group consisting of paints, varnishes, printing inks, security inks, textiles, materials for use in military applications, and plastics, wherein the method comprises adding the IR radiation-reflecting pigment of  claim 1  to said material. 
     
     
         25 . A coating composition
 wherein   the coating composition comprises the IR radiation-reflecting pigment of  claim 1 .   
     
     
         26 . The coating composition of  claim 25 ,
 wherein   the coating composition is a paint, ink, emulsion paint, or plastic.   
     
     
         27 . An article
 wherein   the article is coated with the IR radiation-reflecting pigment of  claim 1 .   
     
     
         28 . The IR radiation-reflecting pigment of  claim 6 , wherein the dark color pigments are present in an amount of 30% to 70% by weight, based on the weight of the total IR radiation-reflecting pigment. 
     
     
         29 . The IR radiation-reflecting pigment of  claim 7 , wherein the dark color pigments are present in an amount of 0.3 to 10 g per 1 m 2  of the surface area of the IR radiation-reflecting core in the IR radiation-reflecting pigment. 
     
     
         30 . The IR radiation-reflecting pigment of  claim 7 , wherein the dark color pigments are present in an amount of 0.5 to 7 g per 1 m 2  of the surface area of the IR radiation-reflecting core in the IR radiation-reflecting pigment. 
     
     
         31 . The IR radiation-reflecting pigment of  claim 13 , wherein the metal is selected from the group consisting of aluminum, copper, zinc, iron, silver and alloys thereof. 
     
     
         32 . The coating composition of  claim 26  wherein the coating composition is an ink and the ink is a printing ink or a security ink. 
     
     
         33 . An article, wherein the article is coated with the coating composition of  claim 25 .